Eli Lilly and partner Incyte have announced that the US Food and Drug Administration (FDA) has declined to approve a new drug, baricitinib, to treat moderate-to-severe rheumatoid arthritis (RA).
RA is a systemic autoimmune disease characterised by inflammation and progressive destruction of joints and more than 23 million people worldwide suffer from this disease.
The FDA has issued a complete response letter for the new drug application (NDA) submitted by the companies for the investigational medicine baricitinib.
Lilly Bio-Medicines president Christi Shaw said: "We are disappointed with this action. We remain confident in the benefit / risk of baricitinib as a new treatment option for adults with moderate-to-severe RA.
"We will continue to work with the FDA to determine a path forward and ultimately bring baricitinib to patients in the US."
The once-daily oral JAK inhibitor baricitinib is currently in clinical studies for inflammatory and autoimmune diseases.
It is being studied in Phase II trials for atopic dermatitis and systemic lupus erythematosus, while a Phase III trial for patients with psoriatic arthritis is expected to be initiated this year.
JAK1, JAK2, JAK3 and TYK2 are the four known JAK enzymes.
Cytokines that are dependents on JAK have been implicated in the pathogenesis of several inflammatory and autoimmune diseases, suggesting that the inhibitors may be useful to treat a range of inflammatory conditions, including RA.
In its letter, the FDA indicated that the companies are required to provide additional clinical data to determine the appropriate doses.
It also stated that in order to further characterise safety concerns across treatment arms, more data is needed.
In January last year, Lilly and Incyte submitted the NDA for baricitinib to the FDA and announced a three-month extension by the agency in January this year to allow time for a review of additional data analyses.